Shoulder pain following stroke is a major rehabilitation problem affecting approximately 60% of moderate to severely impaired stroke survivors. The investigative team recently demonstrated the efficacy of percutaneous intramuscular (IM) electrical stimulation (ES) in treating post-stroke shoulder pain. However, only those individuals enrolled within 18-mo of their stroke experienced enduring treatment effect. Participants enrolled after this 18-mo period experienced significant pain reduction at the end of treatment, but the therapeutic benefit did not persist in the long-term. This population may benefit from a fully implanted ES system. A phase I feasibility trial is proposed to demonstrate the safety and initial efficacy of a Two-stage Implanted ES system for the treatment of shoulder pain for those who are greater than 18-mo from stroke. During the Trial Stage, stroke survivors who experience short-term benefit from percutaneous IM ES will be identified. During the Implant Stage, these participants will receive the fully implanted ES system and be followed for 6-mo. Outcomes measures will include the Brief Pain Inventory question 12, radiographic glenohumeral subluxation, Fugl-Meyer Motor Assessment and the Arm Motor Ability Test.